Question

I would like to find each integer coordinate point between 2 set of coordinate points.

For example, I need the coordinates between (2,15) (6,15). It should give me (3,15) (4,15) (5,15)
. I cannot find any math formula or c++ code that does this.

I want all the coordinates on the line connecting the two points where both X and Y happen to be integers

(6,15)&(6,17) = (6,16)

The coordinates form a shape such as Rectangle or cross and the basic idea is to get the coordinates between each set of coordinates.

Rectabgle Shape
Point [1] : (2, 17)
Point [2] : (2, 15)
Point [3] : (6, 15)
Point [4] : (6, 17)

Points on perimeter : (2, 16), (3, 15), (4, 15), (5, 15), (6, 16), (5, 17), (4, 17), (3, 17)

Hope this explains better on what I want to achieve.

Answer 1

Trying to find all the coordinates on the line connecting the two points where both X and Y happen to be integers:

First, as another poster pointed out, you need to put this in the form y = mx + b:

int StartX = 0;
int StartY = 10;
int EndX = 100;
int EndY = 110;

// m = rise / run
float m = 0.0;

if (EndX == StartX || EndY == StartY)
{
    // add code here to handle the trivial cases
    return;
}

int run = EndX - StartX;
int rise = EndY - StartY;
m = ((float) rise) / ((float) run);

// solve for b
// (start with y = mx + b, subtract mx from both sides)
float b = StartY - (m * StartX);

Now iterate:

// note: assumes EndX > StartX
for (int x = StartX; x <= EndX; ++x)
{
    // solve for y
    float y = (m * x) + b;

    // round to nearest int
    int rounded = (y > 0.0) ? floor(y + 0.5) : ceil(y - 0.5);

    // convert int result back to float, compare
    if ((float) rounded == y)
        printf("(%d, %d)\n", x, rounded);
}

This code is not tested, and it fails if EndX < StartX, but it should get you started. If someone has a better comparison method, let me know and I’ll include it.

Edited to add

The question has been closed, probably because it was not stated clearly, but I’ve added a line to show where you need to handle StartX == EndX and StartY == EndY.